The present invention relates to a communication base station, and more specifically, to a base station system and a radio unit and a baseband processing unit therein.
Wireless communication technology develops rapidly in recent years, and a base station system can provide users with various enhanced services via wireless communication.
FIG. 1 shows a structural diagram of a typical base station system. As shown in FIG. 1, the base station system comprises a radio unit 10 and a baseband processing unit 20. Generally, the radio unit 10 is remote from the baseband processing unit 20, and is therefore referred to as Remote Radio Unit. The base station system transmits and receives radio signal via the radio unit 10 so as to communicate with mobile terminals. Specifically, the radio unit 10 receives uplink data signal from mobile terminals via an antenna and a receiver, and converts analog uplink signal to digital signal via an Analog-to-Digital Converter (ADC). Then, the radio unit 10 transmits digitalized uplink data signal to the baseband processing unit 20 for further processing. In general, an adapter is also disposed between the radio unit 10 and the baseband processing unit 20 for exchanging and forwarding of data. The radio unit 10 transmits uplink data to the baseband processing unit via that adapter, which is not shown herein for brevity.
Since the baseband processing unit 20 typically performs baseband processing on signal in frequency domain, whereas what is directly obtained by the radio unit 10 is often signal in time domain, the baseband processing unit 20 usually comprises a Fourier Transformation Unit (DFT) for transforming uplink data signal in time domain obtained from the radio unit 10 into uplink data signal in frequency domain. Then, after the transformation by the DFT unit, the baseband processing unit 20 can conduct further baseband processing on uplink data signal in frequency domain. The above is the brief description for processing procedure of uplink data signal in the radio unit 10 and the baseband processing unit 20.
As to downlink processing, the downlink data signal after baseband processing is first obtained in the baseband processing unit 20, and transformed from frequency domain to time domain via an Inverse Fourier Transformation Unit (IDFT), and then the downlink data signal in time domain is sent to the radio unit 10. After obtaining the downlink data signal in time domain, the radio unit 10 first converts it into analog signal via a Digital-to-Analog Converter (DAC), then transmits the modulated signal to mobile terminals via the transmitter and antenna. Thus, via the above uplink and downlink, mobile terminals are capable of exchanging data with the base station system to realize communication.
As mentioned above, generally, the radio unit 10 is remote from the baseband processing unit 20, and therefore, the two usually communicate with each other via communication media such as optical fiber that is suitable for long-range communication. However, with the rapid development of communication technology in recent years, service provided and data traffic processed by the base station system increase exponentially. In particular, with the emergence of third and fourth generation mobile communication technology such as Long Term Evolution (LTE) and Long Term Evolution Advanced (LTE-A), radio spectrum width becomes larger and larger. Meanwhile, due to the ability of supporting advanced technology such as Multi-Input Multi-Output (MIMO), bandwidth required to transfer baseband signal between the baseband processing unit 20 and the remote radio unit 10 becomes larger and larger. Specifically, under LTE technology supporting spectrum width of 20 MHz and 2*2 MIMO, 2 Gbps transmission bandwidth is needed between the baseband processing unit and the radio unit. If the above technology is made to support 8*4 MIMO, then the bandwidth needed will be increased to about 8 Gbps. It can be anticipated that, with further improvement in Quality of Service, baseband signal traffic between the baseband processing and the radio unit will be further increased, which will bring huge pressure on communication bandwidth. Therefore, it is desirable to propose a solution that reduces communication bandwidth pressure between the baseband processing and the radio unit without reducing Quality of Service.